Volatile Single-Source Molecular Precursor for the Lithium Ion Battery Cathode

The first single-source molecular precursor for a lithium–manganese cathode material is reported. Heterometallic β-diketonate LiMn₂(thd)₅ (1, thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) was obtained in high yield by simple one-step solid-state reactions employing commercially available reagents. Substantial scale-up preparation of 1 was achieved using a solution approach. The crystal structure of the precursor contains discrete Li:Mn = 1:2 trinuclear molecules held together by bridging diketonate ligands. The complex is relatively stable in open air, highly volatile, and soluble in all common solvents. It was confirmed to retain its heterometallic structure in solutions of non-coordinating solvents. The heterometallic diketonate 1 was shown to exhibit clean, low-temperature decomposition in air/oxygen that results in nanosized particles of spinel-type oxide LiMn₂O₄, one of the leading cathode materials for lithium ion batteries.